Last weekend, I waxed and polished my car, and she was looking mighty sexy. To finish things off, I degreased the engine bay, and as I was finishing up, I was LIGHTLY wiping over some hoses in the back of the bay, and the coolant hose going to the heater core came loose and sprayed hot coolant all over my face and arm. I was initially pissed due to the pain and poor connection of the hose, but I reclamped it down and everything was fine. However, when I push the car at all, the hose busts loose and I lose all my coolant (nothing was harmed, temp gauge never made it above half before I shut it off). So yeah, basically now, I clamp it down, and it comes off if I push the car. However, since the last time I did it, it's stayed on and I even went WOT a few times. I'm gonna take it to Ford anyway and have them seal it up for good. Not something I want coming off in the middle of nowhere and potentially harming my engine.
/rant
/rant
i'd be pretty pissed if that happened to me after i just spent 6k at a dealership for a new engine, only to have their poor workmanship risk ruining your new motor 
if they do end up tryin to charge you for the manifold, take a look around online first for one, its usually cheaper -.-